2.3.4.3 The RowIndex

The hidRowIndex member in TCINFO points to an embedded BTH that contains an array of (dwRowID, dwRowIndex) value pairs, which provides a 32-bit primary index for searching the Row Matrix. Simply put, the RowIndex maps dwRowID, a unique identifier, to the index of a particular row in the Row Matrix.

The RowIndex itself is a generic mechanism to provide a 32-bit primary key and therefore it is up to the implementation to decide what value to use for the primary key. However, an NID value is used as the primary key because of its uniqueness within a PST.

The following is the layout of the BTH data record used in the RowIndex.